The present invention generally relates to devices for cleaning compressed gas, particularly to devices for cleaning and drying compressed gas, more particularly to devices for cleaning and drying compressed air, and most specifically to devices for cleaning and drying compressed air systems for trucks and the like.
The need to collect and remove air system contaminants in solid, liquid and vapor form before they enter the air system has been long recognized. However, various devices attempting to solve this need have many shortcomings. As examples, such prior devices required top access for servicing the unit. Since the devices are typically mounted to the undercarriage of the truck where top access is limited, it was often necessary to remove the device from the truck and the air system to allow servicing, which is very time consuming and often results in breakage of the air conduits or other parts of the air system. Another problem of the prior art is the inefficiencies of the desiccant material. Specifically, prior devices often left the purge valve open to the atmosphere for long periods of time such as whenever the compressor was in an unload mode. Due to its affinity to moisture, the desiccant material would absorb moisture from the atmosphere when the purge valve was open, especially during very humid days, and the desiccant material would then have reduced ability to absorb moisture when on line with the air system during the drying cycle. Also, the desiccant material in prior devices would develop dead spots because the regeneration air would not remove moisture from all locations of the desiccant material during the regeneration cycle due to channeling in the desiccant material and other problems. Further, the regeneration cycle of the desiccant material in prior devices was often inefficient at the removal of moisture. Furthermore, regeneration of the desiccant material in prior devices was often limited by the contamination of the desiccant material such as by oils which are absorbed by but which are not released by the desiccant material. Although various approaches have been utilized to prevent such contamination, they have been ineffective in doing so. Additionally, prior devices have been of a relatively large size which restricts their potential installation locations. Further, prior devices have been of a complicated design requiring extensive controls for the regeneration cycle, compressor isolation valves to prevent turbo rush, regeneration storage reservoirs for regeneration air since an insufficient amount of regeneration air was available, and other such structures. Another major problem was that often the need for servicing prior devices was first noticed only after or because contamination was belatedly noticed in the system downstream from the device, therefore requiring extensive reconditioning of the air system to purge it of these contaminants. Thus, with these and other problems and disadvantages of prior devices, a continuing need exists for devices for collecting and removing contaminants from compressed gas systems which overcomes the many shortcomings of prior attempts to solve this need.